I lost my pport and I don't have a birth certificate!?

Okay so I was born in Quito, Ecuador but I am an US citizen because I was born abroad to US parents... I just lost my pport but I do have an expired pport from when I was 8 years old, can I use that to get a new one? I really need my pport because I am trying to join the Air Force.. Does anybody know what I can do? Thank you!!